Cathodic protection is commonly applied to protect marine, underground and other corrosion prone metal structures against corrosion. These structures may be water storage tanks, gas pipelines, oil platform supports, railtracks and many other metal facilities exposed to a corrosive environment.
If metal flowlines, pipelines, tanks or other metal structures are buried and/or submerged, soil and/or water conditions, such as salinity, conductivity and porosity have a corrosive effect on the structure causing it to loose metal to the surrounding soil or water. To inhibit this corrosion, metal structures may be protected against corrosion by the application of a sacrificial anode system in which a more active metal in the galvanic series than that of the structure is used as a sacrificial anode or by an Impressed Current Cathodic Protection (ICCP) system wherein a electric current is impressed on a buried anode (+), which drives the metal structure to a negative voltage relative to the environment.
The electric current for an ICCP system may be supplied by one or more transformer/rectifier devices, which may supply a direct current (DC) of up to 100 Amps at a voltage of below 1.3 Volt. The voltage is generally maintained below 1.3 Volt to inhibit formation of hydrogen in any water and/or hydrocarbons in the interior and/or exterior of the structure, since the formed hydrogen would also react with the metal of, and thereby cause hydrogen embrittlement of the structure.
It is known from U.S. Pat. No. 6,715,550 and European patent 1252416 to transfer a low voltage alternating current (AC) or Direct Current (DC) via a production tubing or casing in a well to one or more downhole electrical appliances.
However, thus far it has been considered unfeasible to use electrical energy at a voltage of below 1.3 Volt derived from an impressed current cathodic protection (ICCP) system to supply energy to one or more electrical appliances.